Genetic evaluation of gestation length and its use in managing calving patterns

Abstract

Data collected from Australian Holstein cows that calved between 1995 and 2016 were used for estimating genetic parameters and genetic evaluation of gestation length (GL). Genetic parameters were estimated using a sire maternal grandsire model considering GL in heifers as correlated, but a different trait to adult cows and animal repeatability model. The key objective of this study was to assess if selective mating of bulls with short GL estimated breeding values (EBV) can help to modify calving patterns in predominantly pasturebased production systems and thereby contribute to the reduction of calving induction. The mean GL in heifers and adult cows was 280 and 281 d, respectively. The heritability of direct GL was 0.28 in heifers, which is slightly lower than in adult cows (0.36). The maternal heritability of GL was close to 0.04 in both heifer and adult cows. The genetic correlation between direct effects in heifers and adult cows was lower (0.88) than between maternal effects (0.94). A genetic evaluation model that considered heifer and adult cow data as the same trait in a repeatability animal model showed adequate variability in EBV for both direct and maternal GL. The genetic trend in direct GL EBV declined from 2005 in bulls and from 2006 in cows. Selective mating of bulls with short direct GL EBV showed that the GL and calving interval of their mates can be modified by up to 3.5 d for GL and 2.0 d for calving interval. Relative to parent average, the use of genotype data to calculate genomic EBV increased the reliability of EBV by up to 11% in validation bulls when daughter trait deviation of bulls with trait deviation of cows (11%) and deregressed breeding values (8%) were used as response variables. On average, for animals with only genotype data, the GL EBV can be predicted with about 50 to 60% reliability (expected) depending on the response variable (deregressed breeding values or daughter trait deviation and trait deviation) and the size of reference set. Overall, the results of this study show that calving patterns can be made tighter by selectively mating short GL EBV bulls to cows that do not become pregnant early in the mating season. Additionally, better reproductive management and the use of bulls with high female fertility EBV are still crucial for the success of a pasture-based dairy production system.

Improving the accuracy of predictions for cow survival by multivariate evaluation model

“…The data used in the present study was provided by DataGene Pty Ltd (Melbourne, Australia). In Australia, the dominant dairy farming system is a pasture-based seasonal production system with a low level of supplementation (Haile-Mariam and Pryce 2019;Ooi et al 2021). The data consisted of survival TDs for 538 394 pure Holstein and 63 839 pure Jersey cows.…”

Diagnosing the pregnancy status of dairy cows: How useful is milk mid-infrared spectroscopy?

“…The data were also checked for unusual milk fat and protein contents (i.e., 1.5 g/dL of milk < fat < 9 g/dL of milk, 1 g/dL of milk < protein < 7 g/dL of milk) and SCC (0.01% upper values were deleted) following the recommendation of the International Committee for Animal Recording (ICAR, 2017b). Finally, gestation length was restricted to be from 250 to 300 d, because the average for Australian Holsteins is 281 d (Haile-Mariam and Pryce, 2019).…”

Association between gestation length and lactation performance, lactation curve, calf birth weight and dystocia in Holstein dairy cows in Iran

“…There are a number of factors identified to impact GL such as genetics, month of conception (or calving), age and parity of the dam, calf gender, litter size (single vs. double), the number of days in milk, and the level of milk production (Silva et al, 1992;Nogalski and Piwczyński, 2012;Tomasek et al, 2017). Although the GL is not included in genetic evaluations in most countries, several studies have confirmed that genetic variation for GL is large enough to change it through selection (Chud et al, 2014;Silveira et al, 2015;Lacerda et al, 2018;Haile-Mariam and Pryce, 2019). The GL is associated with a number of economically important traits, including lactation performance, productive life, health traits, calving ease and calf mortality (Hansen et al, 2004;Vieira-Neto et al, 2017;Haile-Mariam and Pryce, 2019).…”

“…Although the GL is not included in genetic evaluations in most countries, several studies have confirmed that genetic variation for GL is large enough to change it through selection (Chud et al, 2014;Silveira et al, 2015;Lacerda et al, 2018;Haile-Mariam and Pryce, 2019). The GL is associated with a number of economically important traits, including lactation performance, productive life, health traits, calving ease and calf mortality (Hansen et al, 2004;Vieira-Neto et al, 2017;Haile-Mariam and Pryce, 2019). It has shown that longer GL is associated with higher calf birth weight and a higher rate of dystocia which can result in a higher rate of calf and cow mortality and longer postpartum interval (Meijering 1984;Hansen et al, 2004;Chud et al, 2014;Jamrozik and Miller, 2014).…”